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I have an Asus N550JV, and a few month ago I added extra 8 GB RAM and an SSD. I left the HDD instead of the cd-rom, since I thought it would be more useful for me.

I noticed my laptop now holds much less only on battery, and was wondering if the extra HDD might have such an impact.

Eventually I discovered I don't really need the HDD, so I don't mind removing it if it can actually cause that. Maybe it's worth noting - I haven't used it at all, no I/O actions (except what windows does alone when I'm not asking for it)

In addition, if it does have impact - is the only way is to remove it, or there's a configuration I can set in the disk management / bios to completely disable it?

Thanks!

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    It may be your extra RAM that is draining the power: 8GB of DDR4 will consume something like 3W (an idle SSD normally uses less than a tenth of this), while a typical laptop battery is ~50Wh so, if your battery lasted 3 hours, then the average consumption of the laptop would have been ~17W, which the new RAM increases to 20W. This would knock half an hour off the battery life. These figures are very approximate guesses, and the extra RAM could easily shorten the battery life by up to a third, depending on the precise figures for your system.
    – AFH
    Feb 1, 2017 at 15:53
  • oh, wow, didn't knew it has such an affect. thanks!
    – arieljannai
    Feb 1, 2017 at 18:07
  • Down voter - may explain why?
    – arieljannai
    Mar 9, 2018 at 16:03

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Here is a list of typical power of (almost) all parts of a laptop. The values may vary depending on environment and/or configuration. It's my own measurement.

  • Processor: 3W~35W(common),70W(gaming), depending on model and load. ARM not included
  • RAM(SODIMM): 1W~5W(DDR2),4W(DDR3),3W(LPDDR3,DDR4), same as above
  • GPU: 0W*~50W(common),150W(gaming), same as above (*NVIDIA Optimus and AMD DSG)
  • Screen: 4W~20W, depending on model, size and brightness
  • SSD: Less than 1W at idle, up to 5W at full load
  • HDD (2.5"): Less than 1W at idle, up to 5W at full load
  • External Drive: Refer to above
  • DVD Drive: 0W at idle, up to 4W at full load
  • Cooling fan: 0W~5W(common),10W(gaming) each, depending on load
  • Built-in amplifier: 0W~5W, depending on loudness
  • USB Flash Drive: 50mW~1W, certain high-end drives (SanDisk CZ80) can reach 3W
  • LED indicators: Several mW for each
  • Motherboard: 1W~4W, depending on almost everything
    Note: Less than 1W means 100mW to 800mW, dependent
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I'm inclined to think the extra RAM is the issue.

A new SSD should not increase power consumption noticeably; in fact, because the HDD is now mostly idle, power consumption should actually be lower as the power consumed by a busy HDD is typically much higher than the power consumed by a busy SSD for the same task.

On the other hand, because RAM must be continuously refreshed, adding RAM can visibly hurt battery life. The N550JV uses 1.35V DDR3L memory; while this is better than the 1.5V DDR3 memory used on many older systems, it still adds about 2-3 watts to the system's power consumption, especially when under load. On mainstream laptops like this, even a slight increase in power can noticeably hurt battery life.

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  • Good to know that. Maybe you know if there's a way to temporarily disable one of the RAM slots? So if I'm not doing anything that requires much RAM, the battery will last longer
    – arieljannai
    Feb 2, 2017 at 12:53
  • Unfortunately, not as far as I know. Windows can be configured to use less RAM (using msconfig), but the processor's IMC will still have to refresh it. It might help a bit as it won't be accessed, but you probably still won't get full battery life. You'll also need to reboot to make changes of this sort, which may negate any battery life gain. Can you tell us what kind of battery life you used to get and what you get now?
    – bwDraco
    Feb 2, 2017 at 12:56
  • Also, make sure you actually installed 1.35V DDR3L memory! Fourth-generation (Haswell) Intel Core processors require 1.35V memory. If it's 1.5V DDR3 memory you just added, it's out of spec for your system's processor (and may also cause any existing low-voltage memory to run at full voltage). This means your power consumption will go way up and you may even shorten the processor's lifespan.
    – bwDraco
    Feb 2, 2017 at 13:02
  • I checked, and it's indeed 1.35 installed. I didn't knew how to check the L part (I check with z-cpu). The laptop used to last about 3-4 hours (when new) if I remember correctly, and now it's 2 hours. Although it's not new and I'm aware that the battery life decrease with the battery age, for me, it still seems to be a dramatic decrease
    – arieljannai
    Feb 6, 2017 at 13:34

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